According to one source (http://www.dimensional.com/~gizmo42/threlk.html) Gaskarth is an old English name derived from"...goose garth (enclosure), presumably denoting the situation of the cottage where the man lived who was first given this name..."

Thessalie is a French version of Thessalia (rendered as Thessaly in English), a fertile region in in east-central Greece. The region was home of the Centaurs.